Field of the Invention
The present invention relates to an image formation apparatus including a paper feed unit such as a paper feed tray and a paper feed cassette. In particular, the present invention relates to an image formation apparatus such as a copying machine, a printer, a facsimile, or the like provided with an image formation portion which forms an image utilizing an electrophotographic system, irrespective of the type such as color/monochrome images.
Description of the Related Art
Conventionally, an image formation apparatus in which a paper feed unit for housing paper of various sizes is detachably provided to an apparatus body has been known. In such an image formation apparatus, a detection portion for detecting the size of paper housed in the paper feed unit is generally provided to the apparatus body, and in that case, a detection portion using a push switch is often utilized.
For example, Japanese Laid-Open Patent Publication No. 06-298379 discloses an image formation apparatus in which an apparatus body is provided with a plurality of push switches, and a paper feed tray is provided with an operation portion that can be operated by a user in accordance with housed paper, and a switch depression portion that can adopt states indicating a plurality of different codes in cooperation with an operation in the operation portion. The image formation apparatus is configured such that each of the codes is obtained by mounting the paper feed tray on the apparatus body and thereby sensing presence or absence of depression on each of the plurality of push switches, and based on the code, paper size and the like can be detected in a detection portion.
On the other hand, Japanese Laid-Open Patent Publication No. 2008-59845 discloses a sensing module using a push switch, which is applicable to various kinds of electronic devices, wherein a push button is arranged in front of a switch portion of the push switch. In the sensing module, the push button is provided to be slidingly movable along a depression direction of the switch portion of the push switch, and an elastic body which elastically biases the push button toward a direction away from the push switch is arranged. Thereby, the sensing module is configured such that, when the push button is depressed, the switch portion of the push switch is turned on, and when depression of the push button is released, the push button returns to an origin position based on the elastic biasing force (that is, restoring force) of the elastic body, and thus the switch portion of the push switch is turned off.